Abstract

We develop a horizontal peak ground acceleration (PGA) predictive equation for the island of Hawaii by applying the Joyner and Boore (1993, 1994) two-stage regression method to a data set that consists of 51 PGA from 22 events. Magnitudes vary from 4.0 to 7.2, and event depths vary from 4 to 14 km. The resulting equation is

log⁡10PGA=0.518+0.387(M−6)−log⁡10r−0.00256r+0.335S,

where PGA is measured in units of g, M is magnitude, r = (d2 + 11.292)1/2, and S is 0 for lava sites and 1 at ash sites. The distance parameter d is the closest distance from the recording site to the surface projection of the fault rupture area and varies from 0 to 88 km for the Hawaii PGA data set. We find that the attenuation of high- frequency strong ground motion is significantly greater than a previous relationship used for the island of Hawaii. The ash site coefficient S, which represents accelerometer sites with shear-wave velocities that vary from 60 to 200 m/sec, is generally larger than the soil site coefficients in other attenuation relationships.